Detonator locating device



May 27, 1969 D. B. CLL-:LAND 3,446,047

DETONATOR LOCATING DEVICE Filed May l5, 1967 United States Patent O U.S. Cl. 72-56 11 Claims ABSTRACT F THE DISCLOSURE Detonator locating device comprises a body member with an axial bore, to hold the detonator, and a sleeve member.

This may be used for jointing copper tubes into condenser end plates.

This invention relates to a device for positioning and protecting detonators and auxiliary explosive charges in bores, tubes and the like. The invention also includes a method of -using the device for expanding metal tubes, as, for example, into concentric apertures.

In using a detonator to expand a metal tube into, for example, a concentric aperture in another structure as, for example, in the expanding of metal tubes into tubeplates for heat exchangers, condensers or boilers, the detonator must be accurately positioned so that its explosive force is directed with precision towards the portion of the tube being expanded into or 'welded into the other structure. -It is further necessary to provide a pressure transmitting medium between the detonator explosive charge and the portion of the tube to be expanded and to avoid the presence of such transmitting medium between the charge and portions of the tube which must not be expanded as, for example, the portion of condenser tube extending inwardly from the end plate; expansion of this portion would damage the tube and prevent its subsequent removal. It is also desirable to protect the detonator from impact with other bodies whilst it is being placed in position.

We have now devised means for holding a 'detonator firmly in place in a tube, for transmitting explosion pressure from the detonator to the tube and for affording protection to the detonator in handling.

In accordance with the invention a device for locating and protecting an electric detonator in a tube cornprises a body member of explosion-pressure transmitting material, provided with an axial bore adapted in operation to accommodate the end of the detonator casing containing explosive charges and to transmit explosive pressure to a predetermined part of the tubular space, and a sleeve member slidable on the body member so as to surround but be spaced from any portion of the detonator casing extending beyond said bore when said sleeve member is positioned on the body member, said members when thus positioned defining a conduit adapted to permit electrical wires to be led from a detonator within the device to an external position.

The body member of the device may be constructed of any pressure transmitting material but it is preferable to use an elastomeric material since such materials are generally readily moulded and their resilience permits the device to be constructed so that it will bind on the tube in which it is to be located and on the detonator which it is adapted to accommodate. A convenient material is polythene.

Conveniently the body member is provided with a anged or stepped end portion or otherwise provided with an abutment to assist positive location of the sleeve member.

The sleeve member may be open-ended but it is generally preferred to use a closed sleeve member (in the form of a cap) and, to facilitate insertion of the device into a tube, the closed end is preferably domed.

In the method of expanding tubes into apertures using a detonator it is preferred to place the detonator so that the detonation is directed towards the mouth of the tube from which the detonator is inserted and, in devices fior this purpose, it is preferable for the conduit to emerge in the end of the device so that in use the detonator electrical wires do not touch the tube. Conveniently the conduit is a passage between the body member and the sleeve member and may be, for example, a groove in one or other of these members.

When using the device to expand tubes, an electric idetonator, together with any auxiliary explosive charge, if such is required, is placed into the bore of the body member so that its explosive charges are within the bore. The cap member is placed in position on the body member, the electrical leading wires being led through the conduit. The device is then inserted into the metal tube which is to be expanded at the position where it is desired to expand the tube and the detonator is red. The length of the body member is chosen so that it extends over the portion of tube to be expanded but stops short of the portion which must not be expanded. The length of the sleeve member is chosen so that it extends beyond the body member to surround any exposed part of the detonator casing.

In order to further illustrate the invention one preferred device will now be particularly described, by way of example only, with reference to the accompanying drawings in which FIG. l shows diagrammatically a longitudinal section of the device with a detonator in position;

FIG. 2 shows diagrammatically the assembled device position for expanding a tube into a tube-plate;

FIG. 3 shows diagrammatically the tube of FIG. 2 expanded and welded in a tube-plate.

The device, constructed in polythene, comprises a solid cylindrical body member 11 having a lianged end portion 12, an axial bore 13 and a longitudinal peripheral groove 14 forming the conduit to accommodate electrical leading wires. A sleeve member in the form of a domed tubular cap 15 is assembled as a sliding tit over the body member 11 to abut the anged portion 12. As shown in FIG. 1 a detonator casing 1'6 is plugged into the bore 13 so that the detonator explosive charges 17 are within the bore leaving one end extending beyond the bore 13, which end is surrounded by the cap 15. The leading wires 1\8 of the detonator are led through the groove 14 to a position outside the assembly.

In using the device for expanding tubes into tube-plates as shown in FIG. 2, the end of a tube 19 which is to be expanded is inserted into an aperture 20 in a tube-plate 21. The aperture 20 has a frustoconical external portion 22 having a cone angle of about 10. The assembled device as shown in FIG. 1 is inserted into the tube 19I at a predetermined position such that the body member 11 extends over the frustoconical portion 22 but stops short of the internal face 23 of the tube-plate 21. Thus there is a space between the detonator casing '16 and the portion of tube 19 which extends inwardly beyond the body member 11. The size of the device is such that the cap 15 is a sliding fit in the tube 19. It will be apparent that, if an explosive charge is required in addition to the normal detonator charge, it should also be positioned in the bore 13 adjacent to the detonator.

When the detonator is tired by the passage of current through the wires 18 that portion of the end of tube 19 surrounding the body member 11 is expanded and, if sufcient explosive is used, becomes welded to the tubeplate 21 at the frustoconical portion 22, as shown in FIG. 3. The space between the portion of detonator casing 16 outside the bore 13 and the cap 15 prevents transmission of sufcient explosive pressure to the portion of the tube 19 which extends inwardly beyond the body member 11 to cause expansion thereof so that no distortion of the tube occurs which would prevent its removal when desired. The external end portion of the tube 19 extending beyond the body member 11 may be completely severed by the explosion, or may be subsequently trimmed.

What we claim is:

1. A device for locating and protecting an electric detonator in a tube, comprising a body member of explosion-pressure transmitting material, provided with an axial bore adapted in operation to accommodate the end of the detonator casing containing explosive charges and to transmit explosive pressure to a predetermined part of the tubular space, and a sleeve member slidable on the body member so as to surround but be spaced from any portion of the detonator casing extending beyond said bore when said sleeve member is positioned on the body member, said members when thus positioned dening a conduit adapted to permit electrical wires to be led from a detonator within the device to an external position.

2. A device as claimed in claim 1 wherein the pressure transmitting material comprises elastomeric material.

3. A device as claimed in claim 2 wherein the elastomeric material comprises polythene.

4. A device as claimed in claim 1 wherein the body member is provided with an abutment to assist positive location of the sleeve member.

5. A device as claimed in claim 4 wherein the body member is provided `with a anged or stepped end portion.

6. A device as claimed in claim 1 wherein the sleeve member is closed at one end.

7. A device as claimed in claim 6 end of the sleeve member is domed.

8. A device as claimed in claim 1 wherein the body member is adapted to hold the detonator so that detonation is directed towards the mouth of the tube.

9. A device as claimed in claim 8 wherein the conduit emerges in the end of the device.

10. A device as claimed in claim 9 wherein the conduit is a passage between the body member and the sleeve member.

11. A device as claimed in claim 10 wherein the conduit is a -groove in one of said members.

wherein the closed References Cited UNITED STATES PATENTS 3,131,467 5/1964 Thaller et al 29--421 3,290,771 12/1966 Silverman et al 29-421 3,364,562 1/1968 Armstrong 29-421 RICHARD J. HERBST, Primary Examiner.

U.S. C1. X.R. 

